Chemically Modified Carbon Sensors Mixed or Single for the Determination of Cardiovascular Drug Nafronyl Oxalate in Bulk, Praxilene and Human Fluids

Abstract

Three novel modified carbon paste sensors (CMCPs) were proposed for the determination of nafronyl potentiometric in bulk, pharmaceutical dosage form; human plasma/urine. The sensors were based on an ion-pair associates of nafronyl silicotungstic acid (Nf-St) (sensor 1), nafronyl silicomolybdic acid (Nf-SM) (sensor 2), a mixture of [(Nf-St) + (Nf-SM)] (sensor 3). The modified sensors showed Nernstian slopes ranging from 58.5±0.5-60.7±0.5 mV over the concentration ranged from 1.0 x 10-7-1.0 x 10-2 M and pH 2.0-6.0 with a detection limit 0.1 nM. The sensors exhibited good selectivity for nafronyl with respect to inorganic /organic cations, sugars and amino acids. The calibration curve, standard addition and potentiometric titration methods were applied for the determination of nafronyl ion in its bulk powder, pharmaceutical dosage form, and human fluids plasma/urine taken from a healthy volunteer and for the monitoring Praxilene tablets in vitro dissolution rates. Sensor 3 was successfully used for the determination the solubility products of ion-pair associates. The results were excellent and satisfactory recovery comparable to those obtained with the British Pharmacopoeia.